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| United States Patent |
5,674,007
|
|
Bu
, et al.
|
October 7, 1997
|
Method for calculating PMV of air conditioning system
Abstract
A method for calculating a PMV for an air conditioning system having a body
sensor and a temperature sensor includes the steps of sensing a thermal
change a human body senses due to room air circulation using the body
sensor, and converting the sensed thermal change into a digital value,
sensing a room temperature using the temperature sensor, and converting
the sensed room temperature into a digital value, assigning parameters
according to human bodily activities and amount of clothes a man wears
classified by seasons and times, and calculating a PMV by computing the
value of thermal change converted into a digital value, the value of room
temperature converted into a digital value, and the parameters.
| Inventors:
|
Bu; Jong Uk (Seoul, KR);
Shim; Young Cho (Seoul, KR)
|
| Assignee:
|
LG Electronics Inc. (Seoul, KR)
|
| Appl. No.:
|
401208 |
| Filed:
|
March 9, 1995 |
Foreign Application Priority Data
| Mar 09, 1994[KR] | 4578/1994 |
| Current U.S. Class: |
374/45; 236/91C; 374/109; 702/136 |
| Intern'l Class: |
G01K 013/00; G06F 015/00 |
| Field of Search: |
374/109,45
364/557,505
236/91 C
|
References Cited
U.S. Patent Documents
| 3751634 | Aug., 1973 | Madsen | 219/501.
|
| 5170935 | Dec., 1992 | Federspiel et al. | 364/557.
|
| 5291748 | Mar., 1994 | Ueda | 236/78.
|
| 5333953 | Aug., 1994 | Kon | 374/109.
|
| 5374123 | Dec., 1994 | Bu | 374/109.
|
| 5436852 | Jul., 1995 | Kon | 374/109.
|
| Foreign Patent Documents |
| 0495118 | Jul., 1992 | EP | 374/109.
|
Other References
ANSI/ASHRAE Standard 55-1981, pp. 1, 2, 4, 7, 8, 10, 15 & 16 (1981).
|
Primary Examiner: Gutierrez; Diego F.F.
Attorney, Agent or Firm: White; John P.
Claims
What is claimed is:
1. A method for calculating a PMV for an air-conditioning system having a
body sensor and a temperature sensor, the method comprising the steps of:
sensing a thermal change a human body senses due to room air circulation
using the body sensor, and converting the sensed thermal change into a
digital value;
sensing a room temperature using the temperature sensor, and converting the
sensed room temperature into a digital value;
assigning parameters according to human bodily activities and amount of
clothes being worn classified by seasons and times; and
calculating a PMV using the value of thermal change converted into a
digital value, the value of room temperature converted into a digital
value, and the parameters, according to the following equation:
PMV=(a.sub.1 M+b.sub.1 C+c.sub.1)ta-(a.sub.2 M+b.sub.2 C+c.sub.2)S/100-K
where,
M: metabolism,
C: resistivity coefficient of clothes (Clo) value,
ta: room temperature,
S is the output of the body sensor, and
a, b, c, and K are constants.
Description
BACKGROUND OF THE INVENTION
This invention relates to an air conditioning system, more particularly to
a method for calculating a PMV of an air conditioning system, which
detects a room temperature by means of a body sensor and a temperature
sensor to calculate a PMV value.
In general, for an air conditioning system which serves to control room
temperature, a technique for inferring human comfort is an important
factor for achieving a comfortable room temperature.
Herein, besides physical factors such as room temperature, humidity,
convection and radiation temperature, the sense of human comfort is
influenced by 6 parameters including an amount of clothes a man wears and
an amount of metabolism of the man.
As a method for quantifying the sense of comfort, a method for calculating
a PMV has been widely used, which has been formulated by Fanger as
follows.
##EQU1##
where, PMV: Predicted Mean Vote,
M: Metabolism, met(1 met=58/m.sup.2)
W: external activities("0" in most cases)
I.sub.cl : resistivity coefficient of clothes, Clo (1 Clo=0.155 m.sup.2
K/W)
f.sub.cl : ratio of exposed surface area of a human body to the surface
area of clothes.
ta: air temperature, C. deg.
t.sub.r : mean radiation temperature, C. deg.
V: speed of air circulation, m/S
Pa: vapor pressure, Pa
h.sub.c : convection heat transfer coefficient, W/m.sup.2 K
t.sub.cl : surface temperature of clothes, C. deg.
Herein, when the PMV is "zero" it indicates the most comfortable condition.
The air conditioning region recommended by the ISO(International
Standardization Organization) is, in general, -0.5<PMV<+0.5.
In case of managing an air conditioning system using such PMV values, there
are the following two great difficulties.
First, there are difficulties in accurate detection of individual physical
factors of temperature, humidity, air circulation and radiation
temperature, with many sensors required for detecting each of the physical
factors, individually.
Second, there is difficulty of calculating the detected ambient factors.
When the above equations are used for calculating a PMV for a domestic air
conditioner, there are many difficulties in calculating them when the
entire system is not controlled using the same microcomputer.
Meantime, though present domestic air conditioners are provided with a
neuro network technology for the PMV control, in-site measurement is still
difficult.
SUMMARY OF THE INVENTION
The object of this invention is to provide a method for calculating a PMV
using a body sensor and a thermistor temperature sensor.
This and other objects and features of this invention can be achieved by
providing a method for calculating a PMV for an air conditioning system
having sensors, including steps of sensing thermal change a human body
senses due to room air circulation and converting the sensed thermal
change into a digital value, sensing a room temperature and converting the
sensed room temperature into a digital value, assigning parameters
according to human bodily activities and amount of clothes a man wears
classified by seasons and times, and calculating a PMV by computing the
value of thermal change converted into a digital value, the value of room
temperature converted into a digital value, and the parameters.
PMV=(a.sub.1 M+b.sub.1 C+c.sub.1)ta-(a.sub.2 M+b.sub.2 C+c.sub.2)S/100-K(7)
where,
M: metabolism, C: resistivity coefficient of clothes(Clo) value, ta: room
temperature, S is an output of a body sensor, and a, b, c, and K are
constants.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a PMV calculating instrument in accordance
with this invention.
FIG. 2 is a section view of the body sensor of FIG. 1.
FIG. 3 shows an example of PMV values precisely measured for air
circulations and temperatures.
FIG. 4 shows an example of PMV values in accordance with this invention.
FIG. 5 is a graph comparing the precisely measured PMV values to the PMV
values measured in accordance with this invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram of a PMV calculating instrument in accordance
with this invention.
Referring to FIG. 1, a PMV measuring instrument of an air conditioning
system in accordance with this invention, includes a body sensor 1 for
measuring a thermal change of a human body due to a room thermal ambient,
a temperature sensor 2 for sensing a room temperature, a first amplifier 3
for amplifying the output of the body sensor 1 to a certain amplitude, a
second amplifier 4 for amplifying the output of the temperature sensor 2
to a certain amplitude, a first analog/digital converter 5 for converting
an analog output of the first amplifier 3 into a digital output, a second
analog/digital converter 6 for converting an analog output of the second
amplifier 4 into a digital output, a parameter application part 7 for
applying parameters for an amount of clothes a man wears and an amount of
human activities, and a computing part 8 for computing a PMV value based
on the outputs received from the first, and second analog/digital
converters 5 and 6 and the parameter application part 7.
FIG. 2 is a section view of the body sensor of FIG. 1.
The body sensor of FIG. 2, being devised imitating the temperature
controlling mechanism of a human body, is a sensor sensitively reacting to
an air circulation.
The body sensor includes a P.sup.++ layer 12 formed on a silicon substrate
10 having a membrane structure, an oxide film SiO.sub.2 13 and a nitride
film Si.sub.3 N.sub.4 14 formed successively on the substrate, a heater
15, and a temperature sensor 16 for sensing the heat generated by the
heater 15 formed on the nitride film, an oxide film 17 formed on the
nitride film 14 including the heater 15 and the temperature sensor 16, a
black body 18 formed on the oxide film 17 over the heater 15 and the
temperature sensor 16, and an oxide film 11 formed at the back of the
silicon substrate 10.
The oxide film 13 and the nitride film 14 act as insulation films,
supporting films, and films for insulating the heat generated in the
heater, the heater 15 and the temperature sensor 16 are formed on the
supporting films spaced apart for a certain distance. The reference number
19 represents a pad.
The body sensor having the foregoing construction, being preset to generate
a certain amount of heat, senses a thermal change a human body senses due
to room thermal ambient. The temperature sensor 16 senses and outputs the
thermal change due to the heat generated by the heater 15 at change of
room thermal ambient. That is, of the body sensor 1, the heater 15,
collectively reacting to a room thermal ambient, such as temperature,
humidity, air circulation, and radiation temperatures, discharges heat to
outside, and the temperature sensor 16 senses the thermal change of the
heater 15 following such a thermal ambient of the heater. Therefore, an
output of the body sensor 1 is a change of power applied to the body
sensor when an amount of power corresponding to a thermal change of the
heater 15 sensed by the temperature sensor 16 is supplied to the body
sensor 1 for maintaining temperature of the heater 15 to a constant value.
The temperature sensor 16 of the body sensor 1 reacts to temperature,
humidity, and air circulation, especially to the air circulation due to
its construction.
Operation of the PMV measuring instrument having the foregoing construction
is to be explained hereinafter, referring to FIGS. 3-5.
At operation of an air conditioning system, the body sensor 1 detects a
room thermal ambient, wherein, as has been explained, the heater 15 of the
body sensor 1 discharges heat corresponding to a change of room air
circulation, and the temperature sensor 16 of the body sensor 1 senses the
heat of the heater changing according to a room thermal ambient. On
sensing thermal change of the heater, an amount of power as much as the
sensed thermal change is supplied to the heater 15 for adjusting heat of
the heater 15, and the body sensor 1 outputs an electrical signal
corresponding to the changed amount power supplied in response to the
thermal change.
The electrical signal from the body sensor 1 is amplified to a certain
amplitude through the first amplifier 3, and applied to the first
analog/digital converter 5.
And the temperature sensor 2 being a thermistor senses room temperature and
outputs it in an electrical signal, which is amplified through the second
amplifier 4 to a certain amplitude, and applied to the second
analog/digital converter 6.
The first analog/digital converter 5 receives the analog signal sensed by
the body sensor 1 through the first amplifier 3, converts it into a
digital signal, and applies it to the computing part 8.
The second analog/digital converter 6 receives the analog signal sensed by
the body sensor 1 through the second amplifier 4, converts it into a
digital signal, and applies it to the computing part 8.
The computing part 8 receives the digital signals from the first, and
second analog/digital converters 5 and 6 as well as the parameters
depending on an amount of clothes a man wears and an amount of human
activities from the parameter application part 7, and computes the
received values into a PMV.
Herein, the parameters depending on an amount of clothes a man wears and an
amount of activities of a man applied from the parameter application part
7 to the computing part 8 are values prepared by studying condition of
clothes a man wears and condition of activities of a man, classified by
seasons and times.
In this time, the computing part 8 performs a computation with a simple
equation at receiving output signals of the body sensor 1 and the
temperature sensor 2, to obtain a PMV value.
FIG. 3 shows PMV values calculated using equation (1) of Fanger vs.
temperatures and air circulations at M=1.2, C=1, and FIG. 4 shows
experimental PMV values calculated using equation (7) in accordance with
this invention vs. temperatures and air circulations at a.sub.1 =0.15,
b.sub.1 =0.15, c.sub.1 =0.4, a.sub.2 =0.75, b.sub.2 =0.6, c.sub.2 =-0.23,
and K=8.75.
Referring to FIGS. 3 and 4, it can be seen that the PMV values obtained by
the Fanger and the PMV values obtained using the body sensor in accordance
with this invention are varying in a good similarity.
Referring to FIG. 3, it can be seen that the PMV values calculated by the
Fanger equation at an identical temperature decreases as the air
circulation increases, and increases as the air circulation decreases. For
a room ambient, a man feels hot as the PMV value rises toward +3, feels
cold as the PMV values drops toward -3, and feels comfortable at around
zero.
On the other hand, referring to FIG. 4, it can be seen that, under a
certain room temperature condition, the PMV values decreases as the signal
values the body sensor has sensed becomes greater, and increases as the
signal values the body sensor has sensed becomes smaller. And, the PMV
value varies depending on the signal values received from the body sensor
at an identical temperature.
Therefore, it can be understood that the PMV values in accordance with this
invention simply calculated using the body sensor and the temperature
sensor makes not so much difference compared to the PMV values calculated
by the Fanger equation.
FIG. 5 is a graph showing PMV values precisely measured using a PMV
measuring device while varying the ambient, such as outside temperature,
flow and speed of cold air, and humidity under a mocking room thermal
condition, and PMV values obtained in accordance with this invention.
Referring to FIG. 5, it can be known that most of the PMV values precisely
measured using the PMV measuring instrument and the PMV values obtained in
accordance with this invention are changing within maximum error of
.+-.0.2.
The deviation between the PMV values precisely measured in dynamic state
and the PMV values in accordance with this invention, is caused by the
responsive characteristics, and they are proven to show almost same value
in static state.
Calculation of each of the constants through simulation comparing FIGS. 3
and 4 result in to obtain following values.
##EQU2##
Therefore, by detecting a change of a room ambient using the body sensor 1
and the temperature sensor, and by calculating a value for the change of
the room ambient through applying the equation (7) with the constant
within the ranges shown above applied, the computing part 8 can compute
the PMV value good for comfortable air conditioning.
In case a PMV value is to be calculated, since this invention explained
above can detect a room thermal ambient using the body sensor and the
temperature, and can easily calculate the PMV value by using a simplified
equation based on the detected room thermal ambient, this invention can be
widely applicable to domestic air conditioners, H/A and B/A because the
reduced amount of calculation allows not only the PMV value calculation
done with only one memory chip, but also the system control done within
the memory chip, an effect of energy saving of 15% compared to the simple
control as well as realization of comfortable air conditioning as sudden
temperature changes are prevented by temperature can be obtained by
controlling the PMV using outputs of the body sensor and the temperature
sensor.
Although the invention has been described in conjunction with specific
embodiments, it is evident that many alternatives and variations will be
apparent to those skilled in the art in light of the foregoing
description. Accordingly, the invention is intended to embrace all of the
alternatives and variations that fall within the spirit and scope of the
appended claims.
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